Pearson Physics Level 20 Unit II Dynamics: Unit II Review ...
Unit ii(dsc++)
52
UNIT-II UNIT-II Topics to be covered Topics to be covered Singly linked list Singly linked list Circular linked list Circular linked list Doubly linked list Doubly linked list Representing Stack with linked Representing Stack with linked list list Representing Queues with linked Representing Queues with linked list list
-
Upload
durga-devi -
Category
Education
-
view
139 -
download
0
Transcript of Unit ii(dsc++)
UNIT-IIUNIT-IITopics to be coveredTopics to be covered Singly linked list Singly linked list Circular linked listCircular linked list Doubly linked list Doubly linked list Representing Stack with linked listRepresenting Stack with linked list Representing Queues with linked listRepresenting Queues with linked list
In array(or lists) are simple data structures used to hold sequence of data.
Array elements are stored in consecutive memory locations. To occupy the adjacent space, block of memory that is required for the array should be allocated before hand.
Once memory allocated it cannot be extended any more. So that array is called the static data structure.
Wastage of memory is more in arrays.
int a[ ]= {50,42,85,71,99};
What’s wrong with Array and Why linked lists?
Disadvantages of arrays as storage data structures:– slow searching in unordered array– insertion and deletion operations are slow.
Because, we have to shift subsequent elements – Fixed size– Wastage of memory
Linked lists solve some of these problems- Linked list is able to grow in size as needed
• Does not require the shifting of items during insertions and deletions.
- No wastage of memory.
Linked ListsLinked Lists
Linked list Linked list is a linear data structure that supports the dynamic
memory allocation( the amount of memory could be varied during its use). It is also dynamic data structure.
Linked list is used to hold sequence of data values. Data values need not be stored in adjacent memory cells each data values has pointer which indicates where its next data
value in computer memory.
An element in a linked list is known as a node. A node contains a data part and one or two pointer part which contains the address of the neighborhood nodes in the list.
Node structure-
• Types of linked list• Depending on the requirements the pointers are
maintained, and accordingly linked list can be classified into three groups
1. Singly linked lists 2. Circular linked lists 3. Doubly linked lists1. Singly linked list in singly linked list, each node has two parts one is
data part and other is address part. - data part stores the data values. - address part contains the address of its next node.
• Structure of singly linked list
10 25002000
20 26002500
30 2367 40 NULL
23672600
2000Header
A NULL pointer used to mark the end of the linked list
The head or header always points to the first node in the list.
Possible operations on singly linked list
1. Insertion2. Deletion3. Traverse\display4. Search5. reverse a linked list6. Copying7. Merging (combine two linked lists)
Insertion in linked list
• There are various positions where node can be inserted.
1. Insert at front ( as a first element)2. Insert at end ( as a last node)3. Insert at middle ( any position)
Singly linked listsNode Structure
struct node{
int data;struct node *link;
}*new, *ptr, *header, *ptr1;
Creating a node
new = malloc (sizeof(struct node));new -> data = 10;new -> link = NULL;
data link
2000
10
new
2000
NULL
1000
header
10 20 30
5
2000
21
1. Insert new node at front in linked listAlgorithm step1- create a new nodeStep2- new->link=header->linkStep3- new->data=itemStep4- header->link=new.Step5-stop
5
New node
2000
1000 1500 2050
1500 2050
1000
2000
Insert new node at end of the linked list
• Algorithm• Step1- create a new node• Step2- ptr=header• Step3- while(ptr->link!=null)• 3.1. ptr=ptr->link• Step4- ptr->link=new• Step5- new->data=item• Step6- new->link=null• Step7-stop
Insert new node at end of the linked list
2300
header
10 20 30
40
2500
ptr
12300 2400
2400
2450
2450
New
2500
AlgorithmStep1- create a new nodeStep2- ptr=headerStep3- while(ptr->link!=null) 3.1. ptr=ptr->linkStep4- ptr->link=newStep5- new->data=itemStep6- new->link=nullStep7-stop
Insert new node at any position in linked list• Algorithm
1.Create new node2. ptr=header3. Enter the position 4. for(i=1;i<pos-1;i++) 4.1 ptr=ptr->link; 5. new->link=ptr->link; 6. ptr->link=new; 7. new->data=item 8.stop
10 25002000
20 26002500
30 2367 40 NULL
23672600
2000Header
Inserted position is : 3ptr
5
New node1000
2600
1000
Deletion of a node from singly linked list Like insertion, there are also various
cases of deletion:1. Deletion at the front2. Deletion at the end3. Deletion at any position in the list
Deleting a node at the beginning
if (header = = NULL) print “List is Empty”;else{ ptr = header; header = header -> link; free(ptr);}
10 1800 20 30 1400 40 NULL
1500 1800 1200 1400
1200
1500
header
1500
ptr
1800
Deleting a node at the end
10 1800 20 1200 30 1400 40 NULL
1500 1800 1200 1400
1500
header
ptr = header;while(ptr -> link != NULL){
ptr1=ptr;ptr = ptr -> link;
}ptr1 -> link = NULL;free(ptr);
1500
ptr
18001200
NULL
ptr1 ptr1 ptr1
1400
Deleting a node at the given position
10 1800 20 1200 30 1400 40 NULL
1500
header
ptr = header ;for(i=1;i<pos-1;i++)
ptr = ptr -> link;ptr1 = ptr -> link;ptr -> link = ptr1-> link;free(ptr1);
1500
ptr
1500 1800 1200 1400
Delete position : 31800
ptr1
1200
1400
Traversing an elements of a list
10 1800 20 1200 30 1400 40 NULL
1500 1800 1200 1400
1500
header
if(header = = NULL)print “List is empty”;
elsefor (ptr = header ; ptr != NULL ; ptr = ptr ->
link)print “ptr->data”;
ptr
1500
SLL program#include<stdio.h>#include<malloc.h>void search();void traverse();void deletion();void insertion();int choice,i,pos,item;struct node{int data;struct node *link;}*header,*ptr,*ptr1,*new;
void main(){header=NULL;printf("****Menu****\n");printf("\n1.insertion\n 2.deletion\n 3.traverse \n4.search \n5.exit\n");while(1){printf("\nenter ur choice");scanf("%d",&choice);switch(choice){case 1: insertion();
break;case 2: deletion();
break;case 3: traverse();
break;case 4:search();
break;case 5:exit(0);default:printf("\nwrong choice\n");}//switch}//while}//main
//insertion functionvoid insertion(){new=malloc(sizeof(struct node));printf("\n enter the item to be inserted\n");scanf("%d",&item);new->data=item;if(header==NULL){new->link=NULL;header=new;}//ifelse{printf("\nenter the place to insert the item\n");printf("1.start\n 2.middle\n 3. end\n");scanf("%d",&choice);
if(choice==1){new->link=header;header=new;}//ifif(choice==2){ptr=header;printf("enter the position to place item\n");scanf("%d",&pos);for(i=0;i<pos-1;i++)ptr=ptr->link;new->link=ptr->link;ptr->link=new;}//ifif(choice==3){ptr=header;while(ptr->link!=NULL)ptr=ptr->link;new->link=NULL;ptr->link=new;}//if}//else}//insertion
//deletion functionvoid deletion(){ptr=header;if(header==NULL){printf("\nthe list is empty");}else{printf("\n1.start \n2.middle \n3.end");printf("\n enter the place to delete the element from list");scanf("%d",&choice);if(choice==1){printf("\nthe deleted item from the list is -> %d",ptr->data);header=header->link;}//if
if(choice==2){printf("\n enter the position to delete the element from the list");scanf("%d",&pos);for(i=0;i<pos-1;i++){ptr1=ptr;ptr=ptr->link;}printf("\n the deleted element is ->%d",ptr->data);ptr1->link=ptr->link;}//ifif(choice==3){while(ptr->link!=NULL){ptr1=ptr;ptr=ptr->link;}//whileprintf("\nthe deleted element from the list is ->%d", ptr->data);ptr1->link=NULL;}}}
void search(){int loc=0;ptr=header;printf("\n enter the element to be searched in the list");scanf("%d",&item);while((ptr->data!=item)&&(ptr->link!=NULL)){ptr=ptr->link;loc++;}If((ptr->link==NULL)&&(ptr->data!=item))Printf(“\n element not found”); elseprintf("\n the element found at location %d",loc);}//search()
//traverse functionvoid traverse(){if(header==NULL)printf("list is empty\n");else{printf("\n the elements in the list are");for(ptr=header;ptr!=NULL;ptr=ptr->link)printf(“ %d”, ptr->data);}//else}//traverse
Disadvantage of using an array to implement a stack or queue is the wastage of space.
Implementing stacks as linked lists provides a feasibility on the number of nodes by dynamically growing stacks, as a linked list is a dynamic data structure.
The stack can grow or shrink as the program demands it to.
A variable top always points to top element of the stack.
top = NULL specifies stack is empty.
Representing Stack with Linked List
In this representation, first node in the list is last inserted element hence top must points to the first element on the stack
Last node in the list is the first inserted element in the stack.
Thus, push operation always adds the new element at front of the list
And pop operation removes the element at front of the list.
Size of the stack not required. Test for overflow is not applicable in this case.
10 NULL
1500
1800
1200
1400
20 1400
30 1200
40 1800
50 1500 1100
top
Example:The following list consists of five cells, each of which holds a data object and a link to another cell.
A variable, top, holds the address of the first cell in the list.
/* write a c program to implement stack using linked list */#include<stdio.h> #include<malloc.h> #include<stdlib.h>int push(); int pop(); int display();int choice,i,item;struct node {
int data;struct node *link;
}*top,*new,*ptr;main() { top=NULL;
printf("\n***Select Menu***\n");while(1) {
printf("\n1.Push \n2.Pop \n3.Display \n4.Exit\n5.Count");printf("\n\nEnter ur choice: ");scanf("%d",&choice);switch(choice) {
case 1: push(); break;case 2: pop(); break;case 3: display(); break;case 4: exit(0);case 5: count(); break;default: printf("\nWrong choice");
}/* end of switch */}/* end of while */
}/* end of main */
int push(){
new=malloc(sizeof(struct node));printf("\nEnter the item: ");scanf("%d",&item);new->data=item;if(top==NULL){
new->link=NULL;}else{
new->link=top;}top=new;return;
}/* end of insertion */
int pop(){
if(top = = NULL){printf("\n\nStack is empty");
return;}//ifelse{printf("\n\nThe deleted element
is: %d",top->data);top=top->link;
}return;
}/* end of pop() */
int display(){
ptr=top;if(top= =NULL){printf("\nThe list is empty");
return;}
printf("\nThe elements in the stact are: ");while(ptr!=NULL){printf("\n %d",ptr->data);ptr=ptr->link;}/* end of while */return;
}/* end of display() */
int count(){
int count=1;ptr=top;if(top = = NULL){printf("\nThe list is empty");
return;}while(ptr->link!=NULL){
++count;ptr=ptr->link;
}printf("\n\nThe number of elements in the stack are: %d",count);return;
}/* end of count */
New items are added to the end of the list. Removing an item from the queue will be done from the front.
A pictorial representation of a queue being implemented as a linked list is given below.
The variables front points to the first item in the queue and rear points to the last item in the queue.
Representing Queue with Linked List
10 1800 20 1200 30 1400 40 NULL
1500 1800 1200 1400
front rear
10 1800 20 1200 30 1400 40 NULL
1500 1800 1200 1400
front rear
int enqueue(){new=malloc(sizeof(struct node));
printf("\nenter the item");scanf("%d",&item);new->data=item;new->link=NULL;if(front==NULL) {
front=new; }else{
rear->link=new;}rear=new;return;
}/*end of enqueue */
/*write a c program to implement queue using linked list*/#include<stdio.h> #include<malloc.h> #include<stdlib.h>int choice,i,item;struct node {
int data;struct node *link;
}*front,*rear,*new,*ptr;main() {
front=NULL;rear=NULL;printf("\n\n MENU");printf("\n1.Enqueue \n2.Dequeue \n3.Display \n4.Exit");while(1) {
printf("\nEnter your choice: ");scanf("%d",&choice);switch(choice) {
case 1:enqueue(); break;case 2:dequeue(); break;case 3:display(); break;case 4:exit(0);default:printf("\nwrong choice");
}/*end of switch */}/*end of while */
}/*end of main */
int enqueue(){
new=malloc(sizeof(struct node));printf("\nenter the item");scanf("%d",&item);new->data=item;new->link=NULL;if(front==NULL){
front=new;}else{
rear->link=new;}rear=new;return;
}/*end of enqueue */
display(){
if(front==NULL)printf("\nThe list is
emtpy");else{
for(ptr=front;ptr!=NULL;ptr=ptr->link) printf(" %d",ptr->data);}return;
}/* end of display */
dequeue(){
if(front==NULL)printf("\nThe list is empty");
elseif(front==rear) /*list has single element*/{
printf("\nThe deleted element is: %d",front->data);
front=rear=NULL;}else{
printf("\nThe deleted element is: %d",front->data);
front=front->link;}return;
}/*end ofdequeue*/
Doubly linked list In a singly linked list one can move from the header node to any node in
one direction only (left-right).
A doubly linked list is a two-way list because one can move in either direction. That is, either from left to right or from right to left.
It maintains two links or pointer. Hence it is called as doubly linked list.
Where, DATA field - stores the element or data, PREV- contains the address of its previous node, NEXT- contains the address of its next node.
PREV DATA NEXT
Structure of the node
Operations on doubly linked list• All the operations as mentioned for the singly linked can be
implemented on the doubly linked list more efficiently.• Insertion• Deletion• Traverse• Search.
Insertion on doubly linked list• Insertion of a node at the front• Insertion of a node at any position in the list• Insertion of a node at the end
Deletion on doubly linked list
• Deletion at front• Deletion at any position• Deletion at end
if(header==NULL){
new->prev=NULL;new->next=NULL;header=new;
}
else {new->next=ptr;ptr->prev=new;new->prev=NULL;header=new;}
New 1200
1000
1050
21050
1050 1100 2000
1100 2000 1100
header
ptr
1
1200 10 20 30
5
Insertion of a node at the front
1200
Insertion of a node at the end1. Create a new node2. Read the item3. new->data=item4. ptr= header5. while(ptr->next!=NULL)
5.1 ptr=ptr->next;6. new->next=NULL;7. ptr->next=new;8. new->prev=ptr;
1050
1050
1050 1100 2000
1100 2000 1100
header
ptr
10 20 30
New 1200
40
1200
2000
Insertion of a node at any position in the list1. create a node new2. read item3. new->data=item4. ptr=header;5. Read the position where the element is
to be inserted6. for(i=1;i<pos-1;i++)
6.1 ptr=ptr->next;7. 1 ptr1=ptr->next;7.2 new->next=ptr1; 7.3 ptr1->prev=new;7.4 new->prev=ptr;7.5 ptr->next=new;
Algorithm
header
20 10001010 30 20002020 40 NULL100010 2020NULL
1010 2020 1000 2000
1010 ptr1010 ptr
50 NULLNULL
2200 new
Before inserting a node at position 3
header
20 22001010 30 20002200 40 NULL100010 2020NULL
1010 2020 1000 2000
1010ptr2020 ptr
50 10002020
2200 new
ptr1000 ptr1
After inserting a node at position 3
Algorithm:1.ptr=header2.ptr1=ptr->next;3.header=ptr1;4.if(ptr1!=NULL)
1.ptr1->prev=NULL;5. free(ptr);
header
20 10001010 30 20002020 40 NULL100010 2020NULL
1010 2020 1000 2000
1010
ptr1ptr
20 1000NULL 30 20002020 40 NULL100010 2020NULL
1010 2020 1000 2000
20201010
header
Before deleting a node at beginning
After deleting a node at beginning
header
20 10001010 30 20002020 40 NULL100010 2020NULL
1010 2020 1000 2000
1010
Algorithm:1. ptr=header2. while(ptr->next!=NULL)
1. ptr=ptr->next;3. end while4. ptr1=ptr->prev;5. ptr1->next=NULL;
Before deleting a node at end
ptrpt1header
20 10001010 30 NULL2020 40 NULL100010 2020NULL
1010 2020 1000 2000
1010 20001000After deleting a node at end
Deletion at any position
Algorithm1. ptr=header
1.for(i=0;i<pos-1;i++) 1. ptr=ptr->next;
2. ptr1=ptr->prev;3. ptr2=ptr->next;4. ptr1->next=ptr2;5. ptr2->prev=ptr1;6. free(ptr);
header
20 10001010 30 20002020 40 NULL100010 2020NULL
1010 2020 1000 2000
1010 ptr1010 ptrBefore deleting a node at position 3
After deleting a node at position 3
2000header
20 20001010 30 20002200 40 NULL202010 2020NULL
1010 2020 1000 2000
1010ptr2020 ptr
1ptr1000 ptr2
Displaying elements of a list
Algorithm:1. ptr=header;2. if(header = = NULL)
1. printf("The list is empty\n");3. else
1. print “The elements in farword order: “2. while(ptr!=NULL)
1. print “ptr->data”;2. if(ptr->next = = NULL)
1. break;3. ptr=ptr->next;
3. print “The elements in reverse order: “4. while(ptr!=header)
4.1 print “ptr->data”; 4.2ptr=ptr->prev;5. End while
6. print “ptr->data”;7.end else
20 10001010 30 20002020 40 NULL100010 2020NULL
1010 2020 1000 2000
header1010
ptr
1010
Forward Order : 10 20 30 40
Reverse Order : 40 30 20 10
Circular linked list• In a single linked list the last node link is NULL, but a number of
advantages can be gained if we utilize this link field to store the pointer of the header node.(address of first node).
• Definition- the linked list where the last node points the header node is
called circular linked list.Structure of the circular linked list
Advantages of circular linked list1. Accessibility of a member node in the list2. No Null link problem3. Merging and splitting operations implemented easily 4. Saves time when you want to go from last node to first node.
Disadvantage1. Goes into infinite loop, if proper care is not taken2. It is not easy to reverse the elements 3. Visiting previous node is also difficult
/* Write a c program to implement circular linked list*/#include<stdio.h> #include<conio.h> #include<malloc.h> #include<stdlib.h>int choice,i,item;struct node {
int data;struct node *link;
}*front,*rear,*new,*ptr1,*ptr;main() {
front=rear=NULL;printf("\n select menu\n");while(1) {
printf("\n1.Enqueue \n2.Dequeue \n3.Display \n4.Exit");printf("\nEnter ur choice: ");scanf("%d",&choice);switch(choice) {
case 1: enqueue(); break;case 2: dequeue(); break;case 3: display(); break;case 4: exit(0);default: printf("\nWrong choice.");
}/*end of switch*/}/*end of while*/
}/*end of main*/
int enqueue(){
new=malloc(sizeof(struct node));printf("\nEnter the item: ");scanf("%d",&item);new->data=item;if(front==NULL)
front=new;else
rear->link=new;rear=new;rear->link=front;return;
}/*end of enqueue()*/
dequeue(){
if(front==NULL)printf("\nThe circular list is empty.");
elseif(front==rear)// cll has single element{ printf("\nThe deleted element is: %d",front->data); front=rear=NULL;}else{ printf("\nThe deleted element is: %d",front->data); front=front->link; rear->link=front;}return;
}/*end of dequeue*/
display(){
ptr=front;if(front==NULL)
printf("\nThe circular list is empty.");else{
printf("\nElements in the list are: ");while(ptr!=rear){
printf(" %d",ptr->data);ptr=ptr->link;
}/*end of while*/ printf(“ %d”, ptr->data);
return;}/*end of else*/
}/*end of display*/
